Basis of Presentation - Reclassifications (Details)	3 Months Ended	6 Months Ended
	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($) segment	Jun. 30, 2014 USD ($)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Number of reportable segments | segment		4
Water assets sales price	$ 312,000	$ 10,165,000	$ 7,703,000
Cost of purchased water	135,000	$ 5,483,000	4,524,000
Mineral resources expenses
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Prior year amortization reclassification adjustment	(676,000)
Corporate expenses
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Prior year amortization reclassification adjustment	338,000
Hay Sales, Centennial Operations
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Prior year amortization reclassification adjustment	(138,000)		(404,000)
Hay Sales, Centennial Operations | Cost of Sales
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Prior year amortization reclassification adjustment	$ (191,000)		$ (422,000)